(1) Field of the Invention
The present invention relates to a process for producing an antistatic carpet, more particularly, to a process for producing an antistatic carpet having enhanced durability in the antistatic property thereof.
(2) Description of the Prior Arts
When a person walks on a conventional carpet having a pile surface layer thereof consisting of synthetic polymer fiber yarns or wool yarns, the friction between the carpet surface and the soles of the shoes of the person generates an amount of static electricity which is charged to the person's body. When the person comes into contact with a metallic door knob, the static electricity discharges from the person. This discharge frequently results in a strong electrical shock.
In order to eliminate the above-mentioned disadvantage, various attempts have been made to blend electroconductive fibers in the pile yarns in the carpet. Known electroconductive fibers include metal fibers, organic fibers plated with a conductive metallic material, organic fibers coated with a mixture of an electroconductive substance with a polymeric matrix material, and organic fibers containing therein carbon black particles.
The above-mentioned conventional electroconductive fibers have come into wide use by industry. The conventional fibers, however, have their inherent disadvantages. For example, metal fibers exhibit no or very poor flexual recovery. Therefore, when the metal fibers are repeatedly bent in use or processing thereof, the electroconductivity of the metal fibers significantly decreases. Also, metal fibers are difficult to blend in other types of fibers. Furthermore, the inherent specific color of the metal fibers sometimes degrades the color of the carpet pile layer containing, as a major component, organic fibers dyed in a light color.
As for metal-plated organic fibers, the plated metal layers formed on the organic fiber surfaces should be even and continuous. Therefore, the organic fibers to be plated are required to have a smooth and even surface. Only specific types of organic fibers meet the above-mentioned requirement. Also, the plated metal layer sometimes easily peels off from the organic fiber surface and, therefore, exhibits poor durability. Furthermore, the plated metal layer has a specific color inherent to the plated metal. This specific color of the metal layer is sometimes undesirable.
In the case of conductive fibers in which the organic fiber surfaces are coated with a mixture dope of an electroconductive substance with a polymeric matrix material, the coating layer sometimes easily separates from the organic fiber surface and exhibits an undesirable color derived from the electroconductive substance.
With carbon black-containing electroconductive fibers, the fibers have to contain at least 15% by weight of carbon black to obtain a satisfactory degree of electroconductivity. This large amount of carbon black causes the resultant fibers to be black or dark gray. Accordingly, when the carbon black-containing fibers are used in the pile layer of the carpet which contains, as a major component, light color-dyed organic fibers, the specific dark color of the carbon black-containing fibers degrades the color of the resultant carpet.
It has also been attempted to apply a rubber latex containing electroconductive carbon fibers onto a lower surface of the carpet to provide an electroconductive backing layer.
In another attempt, the electroconductive fibers are blended in a substrate layer on which the pile layer is formed.
However, the conventional carbon fiber-containing backing layer and the conventional electroconductive fiber-containing substrate layer fail to provide a satisfactory degree of antistatic property to carpets.